OK here's the thing:

I have a 2wd offroad vehicle with crappy compression (= no engine braking) and a tall 1st gear (Toyota G52 tranny I think). Scary.

Anyone have any thoughts about the feasibility of sticking, say, a Marlin reduction box between the tranny and the output flange?

Changing R&P is not really an option, since I'm already on 4.88s, and running 7.50r16 tyres; I want to be able to maintain highway driveability, and my current top speed is already only around 130kph (~80mph). I actually need a gear reduction stage.

M'kay...so you see where my problem is? What I'm basically after is something I can bolt on instead of the current output flange which, well, has a lever attached to it...

I would think you need a transmission from a 4wd Toyota to bolt a reduction case on there. The output shaft is too long on the 2wd. (at least this has been found true on the auto transmissions)

Then you would need some sort of output housing to go in place of the transfer case. (never seen anything like this)

The easiest, somewhat bolt-in, off the shelf answer I can think of would be swap in transmission and transfer case from a 4wd truck. Not perfect, not space effecient but   good excuse to go 4wd!

URI......hmmmmm......looks cool!

oh hey how about an exhst. brake. like the ones used on diesel motors?that would slow ya down! and a lot cheaper that a gear box or rebuild. just a

Dom, welcome, you could put a Lower gear transmission in. while these are 4wd types I am sure a 2wd model could be assembled. As usual Marlin will have to give that final answer....
<snip>
We can rebuild the entire gear set with an imported gear set.
New gear ratios: 1st 5.15, 2nd 2.74, 3rd 1.93, 4th 1.00 5th .83 Reverse 4.23
First gear ratio is 34% lower than the stock ratio (5.15 vs. 3.83).
Cost $650.

Still not right; if I went with the 5.15 1st gear, I end up with a crawl gear of 25:1 - still not anything to write home about. Aside from anything else, there's only so much that I can get out of a more or less stock 22R.

What would be ideal, since a complete 4wd transmission is a very tight squeeze, would be a reduction box that bolts to the end of the tranny. That way I keep my "street" gears (which are just right for deep sand floatation), and get some lower gears for when I have some steep hills to climb.

As far as I can tell, the transmission is the 2wd version of the G52, which seems to have a very long "tailcone" - if that could be replaced with a reduction box, it wouldn't affect driveshaft length much, wouldn't affect ground clearance (which is what lets the Uri get away with so much even without a front driveline)...and I wouldn't even have to modify the transmission tunnel beyond drilling a hole. :thumb:

cheers -

dom

http://www.gearvendors.com/

these guys might just do the trick but they are a bit pricey.

i didn't see an application for your specific truck but they may have something for you.

good luck. :up:

Oh ok, I was thinking easy and cheap.   The 4wd G52 + reduction box + machined billet adapter for reduction box to tailhousing or all new billet tail housing that bolts directly to the reduction box. Guess you would need a short output shaft made too.

Doesn't sound so bad if ya say it real fast.  

What you're describing is basically what I'm after. Simplest would be new billet tailhousing straight on reduction box, and modified driveshaft (currently there is no slipyoke, as it's integrated into the tailhousing of the tranny).

What I have discovered is that usually, easy != cheap...prime example is the dual tank system in my HZJ75 Cruiser - braindead operation, utterly reliable, moer expensive in terms of parts...

or something.

Got wheelbase?

ok i think i have it, ,   G-52 3.83 1st gear+pickup crawlbox with 4.7's, + custom tail housing+ 4.88's=88:1
:~~:

:slap:he has 4.88's :psss:and 7.50 16's

good thing I am not a carpenter or have to measure for a living

Got wheelbase?

Enough. About 90" total (never measured it; couldn't say for sure). A lot of it is eaten up by the fact that the drivetrain starts well back from the front "axle"

...but I've still got some space for driveline. Gettin' kinda steep though; I'd really rather not have to add any length without going with a CV or something.

Is that a bad thing? 7.50s are 32" tall when all is said and done, which is taller than some 33s...and 7.50s will withstand abuse like no other tyre.

What about my 105? approach and 45? departure angles? The 40:60 front/rear weight distribution? The 1200kg fuelled kerb weight? The 45 centimetres of front ground clearance under the sump?

Toyota 4wd sprung-over rear axle, Namibian engineered front crossover independent suspension (made of rebar).

The vehicle is more or less stock from the factory this way...

Anyway: yeah; Glen's suggestion amounting to 88:1 is pretty appealing. So, Marlin people; can it be done?

It all sounds good to me....from my earlier post, it can be done. I have a banged up plate you can use. The price would be right too. You need to figure out the length of the output and the flange to use. Your machinists will have to mate those. The plate will evolve around the shaft.

Scott

He He I did